Modular circuit assemblies such as in the form of a drawer containing one or more circuit boards, can be connected to other circuitry in a housing by inserting the circuit assembly into the housing in the manner of pushing in a drawer. Connection is then made between contacts, or terminals, on the insertable circuit assembly, with corresponding contacts or terminals of an inplace circuit assembly that lies within the housing. It would be possible to position the terminals of the two assemblies so that they wipe across one another to make contact as the insertable assembly is initially pushed into engagement with the inplace assembly. However, it would require relatively large terminals to assure that accurate contact is made, which would minimize the allowable number of terminals and increase the contact wear and insertion forces.
To avoid such problems, multiple small terminals have been used which move into positions adjacent and opposite one another but out of direct contact when the insertable circuit assembly is pushed into the housing. Direct contact of the terminals is achieved by deflecting the terminals on one assembly laterally into contact with the terminals on the other assembly. U.S. Pat. No. 3,853,379 by Goodman, which is assigned to the same assignee as the present application, is an example of a system wherein the terminals are sidewardly deflected after the circuit assemblies engage one another.
The sideward deflection of the terminals after the circuit assemblies are engaged, has been accomplished by the use of mechanisms that were manually operable by moving a lever or the like located outside the housing after the insertable assembly had been fully inserted. Such manually operable terminal-deflecting mechanisms have various disadvantages, including the fact that they require a separate manual operation and they require space for a mechanism that is manually operated at the front of the housing, a rod extending to the rear, and a device at the rear for deflecting the terminals. A system that minimized the manual steps required to install a circuit assembly and which minimize the required space, while still permitting contact of terminals only after the insertable assembly engaged the inplace assembly, would be of considerable value.